In liquid crystal display panels, organic EL display panels, electrochromic panels, electronic paper (electronic paper elements) and the like, elements using a glass substrate have been used. In recent years, demand has been shifting from elements using a glass substrate to elements using a transparent plastic film substrate considering lightness, bendability, impact resistance and applicability to larger sizes. However, there is a problem that transparent plastic film substrates are inferior to glass substrates in gas barrier properties to water vapor or oxygen, which may affect the display performance of an element using a transparent plastic film substrate.
In order to overcome such disadvantages of transparent plastic film substrates, it has been proposed to form a transparent gas barrier layer on a transparent plastic film substrate. For such a transparent gas barrier layer, an oxide thin film of Si or Al (SiO2 thin film or Al2O3 thin film) is used to maintain transparency. Further, in producing a transparent gas barrier layer, vacuum deposition processes such as vacuum vapor deposition, sputtering, ion plating and the like are used. However, use of solely a transparent film on which a transparent gas barrier layer is formed causes a problem that cracks or pinholes caused by bending often occur in the transparent gas barrier layer formed of an oxide thin film and gas barrier properties cannot be maintained.
Some proposals have been made for these problems. For example, it is proposed to form a transparent gas barrier layer on a transparent plastic film substrate by a vacuum vapor deposition and then form an organic coating film on the transparent gas barrier layer to form a multi-layered film of the organic coating film, or to devise the composition of the organic coating film (see for example PTL 1).
In electronic paper elements, it is proposed to use a transparent gas barrier laminate film formed by providing a transparent gas barrier layer on a transparent plastic film substrate and then laminating the transparent plastic film substrate on another transparent plastic substrate via a pressure-sensitive adhesive or adhesive (see for example PTL 2).